Hollow conductor



June i8, 1935. w. HfBAssE-rT, JR 2,004,972

HOLLOW CONDUCTOR Filed 0G15. 5, 1931 INVENTOR W/LL/AM #51455 m75? @ma 4U ATTORNEYS Patented June 1s, 193s UNITED STATES APATENT OFFICE to Anaconda Wire York, N. Y.

& Cable Company, New

Application October 5, 1931, Serial No. 566,868

3 Claims.

This invention relates to reinforced hollow electrical conductors and more particularly to conductors of this type of large diameter.

In Bassetts Reissue Patent No. 17,156 of De- 5 cember 11, 1928, a hollow conductor is described in which the outer wall of the conductor is formed of a number of small diameter conducting wires laid in a helical formation to form the continuous cylindrical wall. To prevent collapse of this structure when subjected to tension, bending or other collapsing forces, a reinforcing strip of a width equal to the inner diameterv of the cylindrical structure is placed within the structure and given a twist in the opposite direction to that of the wires forming the cylindrical wall, so that a supporting edge is provided at intervals in the length of each wire and at suflciently frequent intervals to prevent an inward bending of the wire. The effect of this strip is therefore somewhat similar to that of a solid strand or supporting means within the conductor.

However, with conductors having larger vdiameters the supporting of the surface or cylinder forming wires against collapse by a single strip becomes increasingly difficult and less elective, as the distance between the supporting contacts of the wires on the strip increases with the diameter unless the twist of the strands is too 30 steep or too pronounced to give the desiredl resistance to stretching or expansion.

An object of the present invention is to provide a supporting structure for hollow conductors, and a. supported or reinforced hollow con- B5 ductor, of relatively large size, without the use of an excessive amount of metal in the inner supporting structure.

In myrinvention I provide an internal supporting structure made up of a plurality of twistlo ed strips so positioned and proportioned as to form, in effect, a number of strands, the effective supporting areas of which substantially fill the interior of the conductor in much the samev manner as solid strands, and thus form a sub- 5 stantially continuous and effective compression resisting support with a minimum of metal. In the preferred form of theinvention a central strand made up of a cable of small wires is employed about which the twisted strips are sym- J metrically arranged, thereby holding the twisted strips in assembled position with the minimum opportunity for displacement from their symmetrical arrangement. Moreover, conductors of graded diameters may be more easily iobtained with standard widths of` strips by varying or adjusting the cross sectional area of the central strand.

Various features of the invention are illusi trated in the accompanying drawing 'in which Fig. 1 is a cross sectional View of Aa hollow 5 conductor embodying the invention and showing by way of example a central strand surrounded by six twisted strips arranged in symmetrical positions. l

Fig. 2 is a similar view of a conductor in which 10 only four supporting strands are employed, and,

Fig. 3 is a viewsimilar to that of Fig. 2 having four supporting strips, but having a central strand of small cross sectional area illustrating the supporting of a conductor of small diameter 15 withoutdecreasing the width of the strip.

Referring to Fig. 1 of the accompanying drawing the conductor is constructed and built about a central cable or core I0 formed of seven individual wires or strands II. symmetrically 20 disposed about the central cable are six twisted strips I2 which are twisted in such a manner that the side edges of the strips lie *in circular cylindrical surfaces indicated in the lines ,.I3.

The strips I2 are, as indicatedjof an I-shaped 25 cross section. ,Mounted on and enclosing the structure thus formed is a circular ,seriesl of outer wires I4 placed in continuous contact with each other and given a helical twist as described in the above mentioned reissue patent.

It will be observed that the areas within the circles I3 fill the space between the central cable I 0 and the surface Wires I4 in inuch the same way as would six solid cables of the same diameters. 'I'he supporting effect of thisarrange- 35 ment of twisted strips for the outer cylindrical wires is similar to that of a center iilled with solid cables. This, however, is done without the necessity of using solid cables or strands and thus accomplishes the desired result with a min- 40 A imum of metal. Moreover, the cable has greater exibility when a number of individual strands of twisted strips are employed than would be the case if it were attempted to use a single twisted strip of a diameter equal to the inner diameter of the conductor and of a proportionate greater thickness.

The structures illustrated in Figs. 2 and 3 are similar to that of Fig. 1, except in the use of a smaller number of twisted strips and the corresponding elements are similarly numbered. As shown in Fig. 2 the areas of the line I3 need not cover the entire space within the cylinder where the diameter of the conductor is suiliciently small to prevent too great a displacement a about its own longitudinal smaller number of constituent wires or strands.

It will be understood that the above examples are merely for the purpose of illustration and that various modifications may be madeggvithout departing from the invention as defined in the following claims:

1. A hollow electric conductor comprising a series of wires formed into a structure, each Wire having continuous contact with adjacent wires and arranged helically about the axis of said conductor to form a substantially continuous surface and a plurality of strands supporting said cylindrical structure, each strand being formed of a iiatL strip twisted axis sothat the long dimension of the cross section of each strip is in a diametric relation to its own strand at all points along its length, said wires being of a ldiameter substantially less than the diameter of said strand;

2. A hollow electric conductor comprising a series of wires formed into a hollow cylindrical structure, each wire having continuous contact with adjacent wires and arranged helically hollow cylindrical about the axis of said conductor to form a substantially continuous. surface, a, central core within the structure thus formed and a plurality of strands supporting said cylindrical structure, each strand being formed of a at strip twisted about its own longitudinal axis so that the long dimension of the cross section of each stripiis in a diametric relation to its own strand at all points along its length, said wires being of a diameter substantially less than the diameter of said strand.

3. A hollow electric conductor comprising a series of wires formed into a hollow cylindrical structure, each wire having continuous contact with adjacent wires and. arranged helically about the axis of said conductor to form a substantially. continuous surface, a central core within the structure thus lformed and a plurality of strands symmetrically arranged about said core and supporting said cylindrical structure, each strand being formed of a-flat strip twisted about its own longitudinal axis so*A that the long dimension of the cross section of eachl strip is in a diametric relation to its own strand at all points along its length, said wires being of a diameter substantially less than 'the diameter of said strand. A

WILLIAM H. BASSETT, JR. 

